Technical Article


Fundamental Analysis into the Drying of Ceramic Shells – Part 2


by Gavin Dooley & Matthew Everden, REMET Introduction


T


his article is Part 2 from the original article by Manuel Guerra & Gavin Dooley as presented in the June


2020 INCAST. These results showed, for a standard aluminosilicate slurry without polymer, strength increases by 55 % as the drying intervals increase from 1 hour to 4 hours. After 4 hours up to 24 hours, the MOR strength starts to become similar and differences, or further improvements are negligible. This paper will reproduce this


testing in a fused silica shell system. Following this, we will review the effects of two different polymer systems on this trend also.


Materials & Methods Drying intervals used for this project were 1, 2, 4, 8 and 24 hours. The dipping log is shown below in Table 1. All MOR bars have a total of 9 coats, no prime coat was used. MOR testing is then carried out at green, hot (fired at 1000 °C) and fired & cold. Table 2 shows the shell room environmental conditions used to dry


20 ❘ November 2020 ®


Figure 1: MOR versus intercoat dry time as present in the June 2020 INCAST magazine (Aluminosilicate shell)


Type of Dip Stucco Used Coats


Backup Coat Remasil 50 16-30 mesh


Seal Coat


No stucco used


Table 1: MOR dipping log used. 8 1


Parameters Airflow (m/s)


Results 0.6


Humidity (%RH) 45 Temp (ºC)


20.7


Table 2: Environmental Conditions used to dry MOR bars.


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